The present invention relates to a device for printing and, more particularly, but not exclusively to a high-speed printing machine for printing directly onto textiles including the application of print directly onto garments, built in a two dimensional matrix structure.
Screen printing and digital printing are both known methods in the art of garment printing. Mass production of garment decoration is performed today by screen printing press machines as described above, that are complex, inflexible, and require a specific set-up for each different print and color. First, an image file undergoes a mechanical spot-color separation process in which each color is printed in black and white on a separate sheet of paper or film. Then, the image is developed in a long optical process, into a fine mesh or screen, which is pressed during the printing process against the media. Before printing, each screen has to be set in the proper station and adjusted with reference to the other screens. Ink is transferred to the garment through the mesh by mechanical means, generally wiping a squeegee along the screen. Garment screen-printing technology requires a special press station for each color level.
Print quality is limited due to the high registration requirements between stations; hence printing resolution is relatively low. Thus, conventional screen-printing technology is not cost effective for short run processes, especially for sample printing stages.
In a simple screen printing operation the garment or cloth substrate placed on tray is first printed with one color, then moved to a next screen and printed with a second color, etc. To achieve high speed and high efficiency, a modern screen-printing machine has several stations, each station prints one color, and the printed substrates are moved in a sequence from station to station.
Digital printing employs a printing head having several ink injectors, each injector applying one color, so that a single printing head prints all the colors in a single operation. A controller moves the functional unit over the garment (or the garment may move under the functional unit) and instructs the ink injectors when to inject ink. To speed up the printing process, a digital printing system may employ several printing heads concurrently, and a printing head may have hundreds of injectors of the same color.
In screen printing, the fabrication of the screens and the setup of the printing machine, e.g. the mounting of the screens, is relatively slow and expensive. However, the printing itself is fast and inexpensive. Screen printing is therefore suitable for large product quantities. Screen printing can easily employ special colors and special effects such as glitter particles.
Digital printing creates images of higher spatial resolution (i.e. smaller pixel size) and higher color resolution (i.e. many more shades) of each color. The result is an image of much higher quality. Digital printing requires very short preparation prior to printing, however the printing itself is slow and inefficient relative to screen printing.
Printing processes often involve several stages. With textiles in particular, a pre-printing process such as a wetting process may be required; a post printing process such as ironing may be also required.
US patent application No 2005/0179708 A1 by Ofer Ben Zur, Published on Aug. 18, 2005 herein incorporated by reference discloses a digital printer having one digital printing head and two printing tables to allow loading and unloading of a garment as the other garment is printed. Thus down-time of the print head while the printing table is prepared is reduced or eliminated.
U.S. patent application Ser. No. 11/123,201 filled on 6 May 2005 by Feldman Alon et al, herein incorporated by reference, discloses a carousel printer for combining stencil and digital printing. The carousel allows for screen printing stations and digital printing stations together.
Digital garment printers, like the Brother GT541, that print directly on the garment are commonly used for short batches only.
However the fixed size of the carousel allows only for serial operation and requires a complete redesign for addition of stations to suit particular operations.